**Core Concept**
Tocilizumab is an anti-interleukin-6 receptor (IL-6R) monoclonal antibody used in the treatment of rheumatoid arthritis and cytokine release syndrome. IL-6 is a pro-inflammatory cytokine involved in systemic inflammation and autoimmune diseases.

**Why the Correct Answer is Right**
Tocilizumab works by binding to the IL-6 receptor, thereby blocking the action of IL-6 and reducing inflammation. This is particularly effective in conditions like rheumatoid arthritis where IL-6 plays a key role in joint inflammation and destruction. Tocilizumab's mechanism of action is distinct from other biologic agents used in rheumatoid arthritis, such as TNF-alpha inhibitors.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because tocilizumab is not an antibody against IL-1 receptor, which is targeted by other biologic agents like anakinra.
**Option B:** This option is incorrect because tocilizumab is not an antibody against IL-17 receptor, which is targeted by other biologic agents like secukinumab.
**Option C:** This option is incorrect because tocilizumab is not an antibody against IL-1β, which is targeted by other biologic agents like canakinumab.

**Clinical Pearl / High-Yield Fact**
Tocilizumab is also used off-label in the treatment of cytokine release syndrome, a life-threatening complication of CAR-T cell therapy and other immunotherapies. Its use in this context highlights the importance of IL-6 in mediating severe inflammation.

**Correct Answer: C. IL-6 receptor**